Second, I want colors chosen from L*a*b* color space because it makes the perceived brightness consistent across colors. It turns out color-identifiers mode already uses L*a*b* colors. In rainbow-identifiers mode, I configured it like this:

Pretty! You can change the color selection by changing the lightness and saturation constants. I'll try this for a while. Update: [2014-05-15] rainbow-identifiers 0.1.3 now has an option for using L*a*b* colors without needing the above code. Use (setq rainbow-identifiers-choose-face-function 'rainbow-identifiers-cie-l*a*b*-choose-face)

Edit: [2014-05-18] The original post was about rainbow-identifiers mode; I updated it to also show color-identifiers mode.

I'm a long time Emacs user. When using a Mac, I've been using the builds from emacsformacosx.com. After reading about the new features in 24.4, I tried the Emacs nightly builds, and was mostly happy with them, but I somehow messed up my Emacs package configuration in a way that I can't go back to Emacs 23.3. No big deal, right? So I waited for the 24.3.90 pretest to go back to a somewhat "stable" version, and that just came out last week.

The problem is that the emacs 24.3.90 pretest from emacsformacosx.com is triggering a runaway distnoted process on my system, and is also running rather slowly. There are some patches floating around there, but I'd have to build from source. I've also been curious about the Yamamoto Mitsuharu version of Emacs; see this list of features. If I'm going to build from source, I might as well try his version, right?

Many or perhaps all of the smells produced by your body are produced by the bacterial ecosystems living on and in you. Some of these smells are things we can detect; others we're unaware of. Certain strains of skin bacteria attract mosquitos. By altering the ecosystem on our skin, we can repel mosquitos. Cool!

With genetic engineering, we can do even more. We can replace the bacteria that turn sweat into unpleasant smells with bacteria that turn sweat into floral scents! No more deodorant!

Bioluminescent tattoos: using bioluminescent chemicals, your tattoos will glow or pulse, either all the time, or synchronized with a clock, or triggered by movement or light or sound. Imagine going to a dance club with this.

E-ink tattoos: with e-ink particles embedded in your skin, you'll be able to change the pattern by applying an external array of electric fields. You'll place the “printer” on your arm, apply a new pattern, and then it'll hold that pattern until you want to change it.

Biosensor tattoos: with e-ink particles attached to a layer of biosensor molecules, you'll be able to find out what's going on in your blood. You'll set up blocks that are sensitive to 50, 100, 150, 200 mg/dL of glucose, and then by seeing how many bars are “lit up”, you'll have a rough estimate of your blood sugar. You could do this for everything in your bloodstream.